Bitcoin Forum

I've seen some pretty cool and creative signatures on here... Do people use tools to create them?

Most people do them manually or with the help of an image to ASCII tool.

I recommend you to check these threads:

https://bitcointalk.org/index.php?topic=1727100.0
https://bitcointalk.org/index.php?topic=2198076.0

I doubt that there is one as people tend to make money so creating a tool (and releasing it) which automates thes process would undercut that  :D

But there is a thread from roslinpl, it teaches some very neat tips and tricks for creating a good signature.
It's very detailed and I thought that you could add to it  :)

Maybe others signature designer using photoshop to make a image became pixel art.
But you can use such a web app to help you to create your signature design like Symbol list (https://www.compart.com/en/unicode/) (full list of symbol that you can attach to your sig design) , Gradient BBcode colorizer (https://www.stuffbydavid.com/textcolorizer)( a tool that you can make a gradient color in hex color code) and letter count (https://www.lettercount.com/).
Also you must know the signature restrictions for every rank of this forum :

Signature restrictions

There are restrictions on signatures, based on your activity/rank.